Biology Menstrual Cycle

Biology: Menstrual Cycle
4 stages
stage 1
day 1 - 4
bleeding starts
uterus lining breaks down
stage 2
day 4 -14
uterus lining builds up
spongy layer
full blood vessels
ready for fertilised egg
stage 3
day 14
egg developed and released
stage 4
day 14 - 28
uterus wall maintained
day 28 : no egg then uterus lining breaks down
Hormone Control
Follicle Stimulating Hormone (FSH)
produced: pituitary gland
causes
egg matures in one of the ovaries
ovaries produce oestrogen
Oestrogen
produced: ovaries
causes
inhibits release of FSH
pituitary to produce LH
Luteinsing Hormone
produced: pituitary gland
causes
release of an egg (mid-menstrual cycle)
Hormones in menstrual cycle
Oestrogen & Progesterone in Menstrual Cycle
FSM and LH in Menstrual Cycle
Fertility
Reduce fertility
oestrgen
prevent release of egg
should release egg?
take every day
keeps level high
inhibits FSH production
egg development & production stops
contraception
the pill
oral
Advantages
99% effective
reduces risk of some cancers
disadvantages
not 100% effective
side effects
headache, nausea
not protection against STD
Increase Fertililty
FSH too low
eggs not mature
no egg released
take FSH
stimulate egg production (ovaries)
stimulates oestrogen production (ovaries)
Pituitary gland releases LH
egg released
Advantage
helps increase chance of pregnancy
disadvantage
not always work
expensive
too many eggs
multiple pregnancies
IVF
in vitro fertilisation
womans egg
fertilise by mans sperm
grow into embryo
transfer into uterus
hormones
before egg collection
stimulates egg production
oestrogen / progesterone
implantation into uterus greater success
problems
reaction to hormones
abdominal pain
vomiting
dehydration
increased risk cancer
position unclear
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